2207.7 (A) Works of Unusual Size or Characteristics
If it is impossible or extremely impractical to affix a notice directly to the copies or by means of a durable label because of the size or physical characteristics of the material in which the work is reproduced, a notice is acceptable if it appears on a tag that is of durable material, so as to withstand normal use, and if it is attached to the copy with sufficient durability that it will remain with the copy while it is passing through its normal channels of commerce. 37 C.F.R. § 202.2 (C) (9)(iii).